Method and device for sensing control point on capacitive-type panel

ABSTRACT

For sensing a control point on a capacitive-type panel, first and second voltage signals are respectively received through two sets of receiving lines selected from N receiving lines in response to first and second charge/discharge signals transmitted through two sets of transmitting lines selected from M transmitting lines, respectively, during a specified time period. A characteristic value is generated by operating the first and second voltage signals. Repeat the steps to generate characteristic values for neighboring regions defined by different combinations of transmitting lines and receiving lines. Position information of control point(s) on the capacitive-type panel is estimated accordingly.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation-in-part application claimingbenefit from a parent U.S. patent application bearing a Ser. No.14/162,004 and filed Jan. 23, 2014, contents of which are incorporatedherein for reference.

FIELD OF THE INVENTION

The invention relates to method and device for sensing a control point,and more particularly to method and device for sensing a control pointon a capacitive-type panel.

BACKGROUND OF THE INVENTION

According to different working principles, common touch panels can beclassified into resistive-type touch panels and capacitive-type touchpanels. When a user touches or approaches the surface of thecapacitive-type touch panel with his finger or a conductive object, thecapacitance of the capacitive-type touch panel changes accordingly. Atouch position can be located by sensing and calculating the capacitancechange. A conventional two-dimensional capacitive-sensing touch panel ismainly constituted of two sets of sensing pads respectively arrangedhorizontally and vertically, and the two sets of sensing pads areisolated at their intersected parts with insulating material so thatcapacitors are formed. A two-dimensional capacitive-sensing touch panelis a mainstream among current capacitive-sensing touch panels because itcan detect multiple touch points at the same time so as to meet thedemand on multipoint touch sensing in the market.

SUMMARY OF THE INVENTION

In the conventional sensing technology of the two-dimensional typecapacitive-sensing touch panel, the amount of the sensing pads isincreased and areas of the sensing pads are reduced in order to increasethe sensing resolution. Thus, the amount of sensing pins of a drivingcircuit increases and thus hardware costs increase. A major object ofthe invention is to ameliorate this disadvantage.

The invention provides a method for sensing a control point on acapacitive-type panel, where a conductive object approaches or contacts,the capacitive-type panel including M signal transmitting lines, Nsignal receiving lines and M*N capacitors formed at neighboring regionsof the signal transmitting lines and signal receiving lines, the methodbeing executed by a sensing device and comprising steps of: receiving afirst voltage signal and a second voltage signal through two sets ofsignal receiving lines selected from the N signal receiving lines inresponse to a first charge/discharge signal and a secondcharge/discharge signal transmitted through two sets of signaltransmitting lines selected from the M signal transmitting lines,respectively, during a specified time period, wherein the firstcharge/discharge signal and the second charge/discharge signal are outof phase; and operating the first voltage signal and the second voltagesignal to generate a characteristic value for a neighboring regiondefined by the two sets of signal transmitting lines and the two sets ofsignal receiving lines, wherein the above steps are repetitivelyperformed so as to generate a plurality of characteristic values for aplurality of neighboring regions defined by different combinations ofsignal transmitting lines and signal receiving lines, and positioninformation of at least one control point on the capacitive-type panelis estimated according to the characteristic values.

The invention provides a device for sensing a control point on acapacitive-type panel, where a conductive object approaches or contacts,the capacitive-type panel including M signal transmitting lines and Nsignal receiving lines defining M*N neighboring regions, and the devicecomprising a charge/discharge signal generator electrically connected tothe M signal transmitting lines, the charge/discharge signal generatorinputting a first charge/discharge signal and a second charge/dischargesignal respectively to two sets of signal transmitting lines selectedfrom the M signal transmitting lines during a specified time period,wherein the first charge/discharge signal and the secondcharge/discharge signal are out of phase; and a voltage signal processorelectrically connected to the N signal receiving lines, the voltagesignal processor receiving a first voltage signal and a second voltagesignal respectively from two sets of signal receiving lines selectedfrom the N signal receiving lines during the specified time period,operating the first voltage signal and the second voltage signal togenerate a characteristic value for a neighboring region defined by thetwo sets of signal transmitting lines and the two sets of signalreceiving lines, wherein the above steps are repetitively performed soas to generate a plurality of characteristic values for a plurality ofneighboring regions defined by different combinations of signaltransmitting lines and signal receiving lines, and position informationof at least one control point on the capacitive-type panel is estimatedaccording to the characteristic values.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more readily apparent to those ordinarilyskilled in the art after reviewing the following detailed descriptionand accompanying drawings, in which:

FIG. 1 is a schematic diagram showing a capacitive-type panel where anembodiment of a control point sensing device according to the inventionis adapted to be used;

FIGS. 2A-2C are a flowchart showing steps of an embodiment of a controlpoint sensing method according to the invention;

FIG. 3A is a schematic diagram showing a portion of the capacitive-typepanel as illustrated in FIG. 1 for illustrating an embodiment of controlpoint sensing method operating in the capacitive-type panel;

FIG. 3B is a waveform diagram showing signals associated with thecontrol point sensing method as illustrated in the flowchart of FIGS.2A-2C;

FIGS. 4A-4D are schematic diagrams showing examples of characteristicvalue arrays generated in the control point sensing method asillustrated in the flowchart of FIGS. 2A-2C;

FIG. 5 is a functional block diagram schematically showing anexemplified use of a control point sensing device according to theinvention in a panel requiring more than one chip for sensing control;

FIG. 6 is a functional block diagram schematically showing anotherexemplified use of a control point sensing device according to theinvention in a panel requiring more than one chip for sensing control;

FIG. 7 is a functional block diagram schematically showing a furtherexemplified use of a control point sensing device according to theinvention in a panel requiring more than one chip for sensing control;

FIG. 8 is a schematic diagram showing another comparator circuitaccording to another embodiment of the invention in replacing thecomparator circuit shown in FIG. 1;

FIG. 9 is a schematic diagram showing a portion of the capacitive-typepanel as illustrated in FIG. 1 for illustrating another embodiment ofcontrol point sensing method operating in the capacitive-type panel;

FIG. 10 is a waveform diagram exemplifying signals associated with acontrol point sensing method according to the present invention; and

FIG. 11 is a schematic diagram illustrating an embodiment of thecomparator circuit shown in FIG. 3A and/or FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will now be described more specifically with reference tothe following embodiments. It is to be noted that the followingdescriptions of preferred embodiments of this invention are presentedherein for purpose of illustration and description only. It is notintended to be exhaustive or to be limited to the precise formdisclosed.

Please refer to FIG. 1, in which circuitry of a capacitive-type panel isschematically illustrated. As shown, M signal transmitting lines 11˜1Mand N signal receiving lines 21˜2N are vertically and horizontallyallocated, respectively, and M*N capacitors C11˜Cmn are formed atneighboring regions (in this embodiment, crossover regions, but can alsobe parallel in the same plane) of the signal lines. The proximity ortouch of a user's finger or any other conductive object to one of thecapacitors will result in a capacitance change of the capacitor.According to the sensing method of the invention, the capacitors caneffectively function at capacitances of about 100 fF-10 pF. This showsthat the invention achieves a considerable improvement as compared toprior art which can only function effectively at 1-5 pF. Acharge/discharge signal generator 190 is electrically connected to the Msignal transmitting lines 11˜1M for generating charge/discharge signals,and a voltage signal processor 180 is electrically connected to the Nsignal receiving lines 21˜2N for receiving and further processingvoltage signals generated from the signal receiving lines 21˜2N. Inorder to ameliorate the disadvantage of the prior art, a sensing methodincluding steps as shown in the flowchart of FIGS. 2A-2C is provided.

As shown in FIG. 2A, in Step 101, the charge/discharge signal generator190 has a first charge/discharge signal and a second charge/dischargesignal respectively inputted through at least two sets of signaltransmitting lines selected among the M signal transmitting lines 11˜1Mand then the voltage signal processor 180 receives a first voltagesignal and a second voltage signal, which are generated corresponding tothe first charge/discharge signal and the second charge/dischargesignal, respectively, through at least two sets of signal receivinglines selected among N signal receiving lines during a first timeperiod. For example, the two sets of signal transmitting lines can beadjacent signal transmitting lines 12, 13, while the two sets of signalreceiving lines can be adjacent two signal receiving lines 22, 23. Thefirst charge/discharge signal can be a charge signal rising from 0V to3V (refer to FIG. 3B), the second charge/discharge signal can be adischarge signal falling from 3V to 0V (refer to FIG. 3B). The firstvoltage signal and the second voltage signal respectively received fromthe adjacent two signal receiving lines 22, 23 can be compared in acomparator circuit 18 shown in FIG. 1 and then a first voltagedifference value or a function value equivalent to the first voltagedifference value is outputted via an output terminal Vo according to thecomparison result of the first voltage signal and the second voltagesignal. For example, a function value with the same polarity butnonlinear to the first voltage difference value can be obtain by adifferent comparing method or circuit; or functions of the first voltagedifference value and the second voltage difference value can be obtainedby adjusting the level of the charge/discharge signal. The details willbe described below.

Next, in Step 102, the charge/discharge signal generator 190 has a thirdcharge/discharge signal and a fourth charge/discharge signalrespectively inputted through the same sets of signal transmittinglines, and then the voltage signal processor 180 receives correspondingthird voltage signal and fourth voltage signal respectively through thesame sets of signal receiving lines during a second time period. Thatis, the two sets of signal transmitting lines are the adjacent signaltransmitting lines 12, 13, while the two sets of signal receiving linesare the adjacent two signal receiving lines 22, 23. In this step, thethird charge/discharge signal is a discharge signal falling from 3V to0V (refer to FIG. 3B), while the fourth charge/discharge signal is acharge signal rising from 0V to 3V (refer to FIG. 3B), and the thirdvoltage signal and the fourth voltage signal respectively received fromthe adjacent two signal receiving lines 22, 23 are compared in thecomparator circuit 18 shown in FIG. 1 so as to output a second voltagedifference value or a function value equivalent to the second voltagedifference value via the output terminal Vo according to the comparisonresult of the third voltage signal and the fourth voltage signal. Forexample, a function value with the same polarity but nonlinear to thesecond voltage difference value can be obtained by a different comparingmethod or circuit; or functions of the third voltage difference valueand the fourth voltage difference value can be obtained by adjusting thelevel of the charge/discharge signal. The details will be describedbelow.

Next, in Step 103, the voltage signal processor 180 generates acharacteristic value of an equivalent capacitor corresponding to aneighboring region of the four sets of signal lines according to thefirst voltage difference value or its equivalent function value and thesecond voltage difference value or its equivalent function value. Inthis embodiment, the characteristic value of the equivalent capacitorcorresponding to the crossover region of the adjacent signaltransmitting lines 12, 13 and the adjacent signal receiving lines 22, 23is generated. For example, the characteristic value of the capacitor C22can be defined as the difference obtained by subtracting the secondvoltage difference value or its function value from the first voltagedifference value or its function value.

The voltage signal processor 180 repeats the above-mentioned Steps101˜103 for all the other sets of signal transmitting lines and all theother sets of signal receiving lines, e.g. adjacent signal transmittinglines and the adjacent signal receiving lines, to generate a pluralityof characteristic values, thereby obtaining a characteristic value arrayA[p, q]. Afterwards, the characteristic value array A[p, q] can be usedto estimate position information of one or more control points on thecapacitive-type panel in a subsequent step, wherein each control pointis a position to which a finger or other conductive object approaches onthe capacitive-type panel. When it is determined that all the requiredsteps for obtaining corresponding characteristic values of all thepositions or all preset positions have been performed in Step 104, thenthe method proceeds to Step 105.

In step 105, the position information of one or more control points onthe capacitive-type panel are estimated according to data pattern of thecharacteristic value array A[p, q]. The control point is a position towhich a finger or other conductive object approaches on thecapacitive-type panel. Step 105 can be performed in a control circuitchip, which includes the voltage signal processor 180, of thecapacitive-type panel. Alternatively, the characteristic value arrayA[p, q] can be transmitted to an information system where thecapacitive-type panel is applied, for example, a notebook computer, atablet computer etc. In this example, step 105 is executed in theinformation system. The details of the above-mentioned technology willbe described hereinafter with reference to FIGS. 3A and 3B, in which acircuit structure and a signal waveform are schematically shown.However, the implementation of the invention is not limited to thefollowing examples. Since in the above-mentioned embodiment a unit to besensed involves adjacent two signal transmitting lines and adjacent twosignal receiving lines, a window 20 covering the crossover regiondefined by four signal lines, e.g. adjacent two signal transmittinglines and adjacent two signal receiving lines, can be moved, as a whole,over the capacitive-type panel for scanning. When the window 20 is movedto the crossover region defined by the signal lines X₀, X₁, Y₀, Y₁, anda relative position of an approaching or contact point of a finger (or aconductor) to the window 20 is substantially an upper right intersection1 of the signal lines X₁ and Y₀, the first voltage difference value andsecond voltage difference value obtained through steps 101 and 102 willbe +ΔV and −ΔV, respectively. Accordingly, the characteristic valueobtained in step 103, i.e. subtracting the second voltage differencevalue from the first voltage difference value, will be +2ΔV. In anothercase that the relative position of an approaching or contact point of afinger (or a conductor) to the window 20 is substantially a lower rightintersection 2 of the signal lines X₁ and Y₁, the first voltagedifference value and second voltage difference value obtained throughSteps 101 and 102 will be −ΔV and +ΔV, respectively. Accordingly, thecharacteristic value obtained in Step 103, i.e. subtracting the secondvoltage difference value from the first voltage difference value, willbe −2ΔV. Alternatively, if a relative position of an approaching orcontact point of a finger (or a conductor) to the window 20 issubstantially a lower left intersection 3 of the signal lines X₀ and Y₁,the first voltage difference value and second voltage difference valueobtained through Steps 101 and 102 will be +ΔV and −ΔV, respectively.Accordingly, the characteristic value obtained in Step 103, i.e.subtracting the second voltage difference value from the first voltagedifference value, will be +2ΔV. Likewise, in the case that a relativeposition of an approaching or contact point of a finger (or a conductor)to the window 20 is substantially an upper left intersection 4 of thesignal lines X₀ and Y₀, the first voltage difference value and secondvoltage difference value obtained through Steps 101 and 102 will be −ΔVand +ΔV, respectively. Accordingly, the characteristic value obtained inStep 103, i.e. subtracting the second voltage difference value from thefirst voltage difference value, will be −2ΔV. On the other hand, when afinger (or a conductor) approaches or contacts the window 20substantially at a position 5, 6, 7 or 8 shown in FIG. 3A, i.e. aposition outside the window 20, the characteristic value obtainedthrough Steps 101˜103 in each case will have the same polarity with thecorresponding position 1, 2, 3, or 4 but a smaller absolute value.

Furthermore, if a finger (or a conductor) approaches or contacts thewindow 20 substantially at a position 9 as shown in FIG. 3A, the firstvoltage difference value obtained in Step 101 and the second voltagedifference value obtained in Step 102 will both be 0 on a condition thatthe charge/discharge signal on the signal transmitting line is strongenough. Accordingly, the characteristic value obtained by subtractingthe second voltage difference value from the first voltage differencevalue in Step 103 will be 0. In a further example that a finger (or aconductor) approaches or contacts the window 20 substantially at aposition 10 as shown in FIG. 3A, since the first voltage differencevalue obtained in Step 101 and the second voltage difference valueobtained in Step 102 are respectively −ΔV and −ΔV, the characteristicvalue obtained by subtracting the second voltage difference value fromthe first voltage difference value in Step 103 will be 0. In this casethat the window 20 is located at the crossover region of the signallines X₀, X₁, Y₀, Y₁, if there is no finger (nor conductor) approachingor contacting the panel, or a relative position of an approaching orcontacting point of the finger (or conductor) to the window 20 issubstantially at a position (4-1), a position (4-2) or a position (4-3),a characteristic value obtained through steps 101˜103 will be 0. In thisway, after the whole capacitive-type panel is scanned with the window 20defined with 2*2 signal lines, a characteristic value array A[p, q] isgenerated, in which characteristic values obtained in theabove-mentioned steps and corresponding to specified positions of thewindow are stored. The characteristic values can be positive, negativeor 0, for example simply represented by +, − and 0.

An analysis is then performed according to the data pattern of thecharacteristic value array A[p, q]. Position information of one or morecontrol point on the capacitive-type panel can be estimated in Step 104.The control point is a position which a finger approaches or contacts onthe capacitive-type panel. For example, if there is no fingerapproaching or contacting the capacitive-type panel, all of the datarecorded into the characteristic value array A[p, q] as obtained in thescanning steps during a preset time period are 0. On the other hand, ifa finger is approaching or contacting an intersection of a signaltransmitting line and a signal receiving line, e.g. X₀ and Y₀, of thecapacitive-type panel, the characteristic value corresponding to thespecified position and eight characteristic values corresponding toeight surrounding positions form a 3*3 data array, e.g. the array asshown in FIG. 4A. Therefore, by performing an operation on a 3*3 dataarray, the position which a finger approaches or contacts on thecapacitive-type panel can be specified. For example, when the result ofthe operation meets a first pattern, e.g. the pattern as shown in FIG.4A, it is determined that the estimated control point is (X₀, Y₀) and anoffset vector associated with the control point is (X₀, Y₀) is 0. Thatis, when the characteristic value array A[p, q] includes a data patternas shown in FIG. 4A, it is realized that there is a control point at(X₀, Y₀). If the characteristic value array A[p, q] includes more thanone data pattern like the one shown in FIG. 4A with zero offset, it isrealized that there exists another control point at a specificintersection of a signal transmitting line and a signal receiving line.

In addition, when a part of the characteristic value array A[p, q] has adata pattern as shown in any one of FIGS. 4B-4D, it is also estimatedthat there exists one control point. The control point is not at theintersection but nearby the intersection (X₀, Y₀) with a second offsetvector 42, a third offset vector 43, or a fourth offset vector 44. Forexample, the data pattern shown in FIG. 4B indicates that a controlpoint is below the intersection (X₀, Y₀) (for example, the position(4-3) shown in FIG. 3), the data pattern shown in FIG. 4C indicates thata control point is at right side of the intersection (X₀, Y₀) (forexample, the position (4-1) shown in FIG. 3), and the data pattern shownin FIG. 4D indicates that a control point is at lower right of theintersection (X₀, Y₀) (for example, the position (4-2) shown in FIG. 3).Therefore, at the same wiring density, the resolution can be increasedto two times at two dimensions, and thus the overall resolution can beincreased to four times.

The examples of the charge/discharge signals shown in FIG. 3B are onlyfor illustration, and it is not limited to falling from 3V to 0V andrising from 0V to 3V. It is also feasible, for example, with one fallingfrom a larger fixed voltage to a smaller fixed voltage while the otherrising from another smaller fixed voltage to another larger fixedvoltage. The details will be described later with reference to FIG. 10.

Since the position detection is performed with two adjacent signaltransmitting lines and two adjacent signal receiving lines, it isnecessary to provide dummy signal lines 10, 20 as shown in FIG. 1 ateach edge of the X-direction and Y-direction of the capacitive-typepanel, so as to perform the above-mentioned operation to the signaltransmitting line 11 and the signal receiving line 21. However, it isnot necessary to provide a capacitor to the dummy signal line. Ofcourse, it is also possible to omit the dummy signal line, and directlymirror the signal transmitting line 12 and the signal receiving line 22to be virtual dummy signal lines 10, 20, so as to perform theabove-mentioned operation to the signal transmitting line 11 and thesignal receiving line 21.

Further, please refer to FIG. 5, which is a functional block diagramschematically showing an exemplified use in more than one sensing chipto control the same capacitive-type panel 50. In FIG. 5 two sensingchips are used as an example, different sets of signal transmitting orreceiving lines Xc1, Xc2 are processed by different sensing chips 51,52, and a reference voltage transmission line 53 is disposed between thesensing chips 51, 52 so as to transmit a reference voltage signal to allsensing chips as a reference. By this way, when performing comparisonoperation to voltage signals, which are generated by the signalreceiving lines belonging to different sensing chips, a consistentreference voltage is provided. The voltage difference values obtained inSteps 101, 102 or the characteristic value obtained in Step 103 can betransmitted by the sensing chips 51, 52 to a microprocessor 54 atback-end, so that corresponding position information of a control pointcan be obtained.

In addition, please refer to FIG. 6. If adjacent signal receiving linesY61, Y62 in a capacitive-type panel 60 belong to different chips 61, 62,a signal transmission line (for example, a transmission line 63 in FIG.6) interconnecting the chips 61, 62 with each other can be used totransmit a voltage signal from adjacent one or more signal lines to theother chip as a reference. On the other way, as shown in FIG. 7, asignal receiving line Y72 between signal receiving lines Y71 and Y73 ona capacitive-type panel 70 is connected to different chips 71, 72, sothat a voltage signal from the signal receiving line Y72 can bereferenced by both chips 71, 72.

Further, please refer to FIG. 8, which is a schematic diagram showinganother comparator circuit instead of the comparator circuit 18 shown inFIG. 1, and a first capacitor 81, a second capacitor 82 and thecomparator circuit 88 are used to perform another comparing method. Indetail, in Step 101, the charge/discharge signal generator 190 has afirst charge/discharge signal and a second charge/discharge signalrespectively inputted through at least two sets of signal transmittinglines selected among the M signal transmitting lines 11˜1M and then thevoltage signal processor 180 receives a first voltage signal and asecond voltage signal, which are generated corresponding to the firstcharge/discharge signal and the second charge/discharge signal,respectively, through at least two sets of signal receiving linesselected among N signal receiving lines during a first time period. Forexample, the two sets of signal transmitting lines can be adjacentsignal transmitting lines 12, 13, while the two sets of signal receivinglines can be adjacent two signal receiving lines 22, 23. The firstcharge/discharge signal can be a charge signal rising from 0V to 3V(refer to FIG. 3B), and the second charge/discharge signal can be adischarge signal falling from 3V to 0V (refer to FIG. 3B). As for thefirst voltage signal and the second voltage signal respectively receivedfrom the adjacent two signal receiving lines 22, 23, two input terminals881, 882 of the comparator circuit 88 are balanced by controlling levelsof an input voltage V81 of the first capacitor 81 and an input voltageV82 of the second capacitor 82 shown in FIG. 8 so that the voltageoutputted by an output terminal 883 is maintained at level “0”, and thedifference of the levels V81 and V82 when the input terminals 881, 882are balanced is obtained as the first voltage difference value.Alternatively, by providing the input voltages V81, V82 with the samevalue but changing the capacitances of the first capacitor 81 and thesecond capacitor 82 can also balance the two input terminals 881, 882 ofthe comparator circuit 88 so that the voltage outputted by the outputterminal 883 is maintained at level “0”, and the difference of thecapacitances of the first capacitor 81 and the second capacitor 82 whenthe input terminals 881, 882 are balanced is obtained as the functionvalue equivalent to the first voltage difference value. Here, thecomparator circuit 18 shown in FIG. 1 needs to be realized by ananalog-to-digital converter; however, the comparator circuit 88 can besimply realized by a single-bit comparator.

Further, in Step 102, the charge/discharge signal generator 190 has athird charge/discharge signal and a fourth charge/discharge signalrespectively inputted through the two sets of signal transmitting linesand then the voltage signal processor 180 receives a third voltagesignal and a fourth voltage signal, which are generated corresponding tothe third charge/discharge signal and the fourth charge/dischargesignal, respectively, through the two sets of signal receiving line. Forexample, the two sets of signal transmitting lines can be adjacentsignal transmitting lines 12, 13, while the two sets of signal receivinglines can be adjacent two signal receiving lines 22, 23. The thirdcharge/discharge signal can be a discharge signal falling from 3V to 0V(refer to FIG. 3B), and the fourth charge/discharge signal can be acharge signal rising from 0V to 3V (refer to FIG. 3B). As for the thirdvoltage signal and the fourth voltage signal respectively received fromthe adjacent two signal receiving lines 22, 23, two input terminals 881,882 of the comparator circuit 88 are balanced by controlling levels ofthe input voltage V81 of the first capacitor 81 and an input voltage V82of the second capacitor 82 shown in FIG. 8 so that the voltage outputtedby an output terminal 883 is maintained at level “0”, and the differenceof the levels V81 and V82 when the input terminals 881, 882 are balancedis obtained as the second voltage difference value. Alternatively, byproviding the input voltages V81, V82 with the same value but changingthe capacitances of the first capacitor 81 and the second capacitor 82can also balance the two input terminals 881, 882 of the comparatorcircuit 88 so that the voltage outputted by the output terminal 883 ismaintained at level “0”, and the difference of the capacitances of thefirst capacitor 81 and the second capacitor 82 when the input terminals881, 882 are balanced is obtained as the function value equivalent tothe second voltage difference value.

In addition, adjacent two signal lines are used as examples fordescription in the above embodiments. Alternatively, two sets or more ofsignal transmitting lines can also be selected from M signaltransmitting lines to respectively input a charge/discharge signal, andcorrespondingly generated voltage signals can be received respectivelyby two sets or more of signal receiving lines selected from N signalreceiving lines. Each set of signal transmitting lines can be consistedof a single signal transmitting line or a plurality of signaltransmitting lines, and the two sets of signal transmitting lines can benot adjacent, but with other signal transmitting lines disposedtherebetween. Of course, each set of signal receiving lines can also beconsisted of a single signal receiving line or a plurality of signalreceiving lines, and the two sets of signal receiving lines can be notadjacent, but with other signal receiving lines disposed therebetween.Sensitivity and area for sensing can be increased by using a pluralityof signal transmitting lines or a plurality of signal receiving lines toform each set of the signal transmitting lines or signal receivinglines, so that a proximity of a conductive object without a direct touchto the capacitive-type panel can be sensed. Alternatively, two sets ormore of signal transmitting lines can also be selected from N signaltransmitting lines to respectively input a charge/discharge signal, andcorrespondingly generated voltage signals can be received respectivelyby two sets or more of signal receiving lines selected from M signalreceiving lines. This can be realized by simply using a multiplexer (notshown) to change the line connections. Further, the voltage signalprocessor 180 can also be constituted by two or more analog/digitalconverters or a single-bit comparator, and the two or moreanalog/digital converters can be disposed on different chips. Since thisis a common modification of the circuit design, is will not be furtherdescribed here.

As described above, a control point on the capacitive-type panel issensed by receiving a first voltage signal and a second voltage signalthrough two sets of signal receiving lines selected from the N signalreceiving lines in response to a first charge/discharge signal and asecond charge/discharge signal transmitted through two sets of signaltransmitting lines selected from the M signal transmitting lines,respectively, during a first time period; receiving a third voltagesignal and a fourth voltage signal through the two sets of signalreceiving lines selected from the N signal receiving lines in responseto a third charge/discharge signal and a fourth charge/discharge signaltransmitted through the two sets of signal transmitting lines,respectively, during a second time period; and generating acharacteristic value for a neighboring region defined by the two sets ofsignal transmitting lines and the two sets of signal receiving linesaccording to the first voltage signal, the second voltage signal, thethird voltage signal and the fourth voltage signal; wherein the abovethree steps are repetitively performed so as to generate a plurality ofcharacteristic values for a plurality of neighboring regions defined bydifferent combinations of signal transmitting lines and signal receivinglines, and position information of at least one control point on thecapacitive-type panel is estimated according to the characteristicvalues. Accordingly, position information of a control point can beaccurately sensed without increasing the number of signal lines.

Different from the sensing method performing two-stage charge/dischargeoperations as described above, another sensing method performing asingle-stage charge/discharge operation is provided according to thepresent invention, which is advantageous in relatively high scanningrate. An embodiment of a method for sensing a control point on acapacitive-type panel, which performs a single-stage charge/dischargeoperation, will be described hereinafter with reference to FIG. 9.

The sensing method can also be applied to a capacitive-type panel havinga structure similar to that shown in FIG. 1, wherein M signaltransmitting lines 11˜1M and N signal receiving lines 21˜2N arevertically and horizontally allocated, respectively, and M*N capacitorsC11˜Cmn are formed at neighboring regions of the signal lines. Adjacenttwo signal transmitting lines and adjacent two signal receiving linesare combined as a unit to be sensed, and a window 20 covering thecrossover region defined by four signal lines, e.g. adjacent two signaltransmitting lines and adjacent two signal receiving lines, can bemoved, as a whole, over the capacitive-type panel for scanning.

The single-stage charge/discharge operation and the two-stagecharge/discharge operation are different in driving ways. Referring tothe example illustrated in the flowchart of FIG. 2A-2C, the two-stagecharge/discharge operation performs a first charge/discharge step 101with a first charge/discharge signal and a second charge/dischargesignal during a first time period, and a second charge/discharge step102 with a third charge/discharge signal and a fourth charge/dischargesignal during a second time period. In contrast, a single-stagecharge/discharge operation omits one of the steps 101 and 102. Forexample, the step 102 is omitted, and only the step 101 is performed byinputting the first and second charge/discharge signals through thesignal transmitting lines X₀ and X₁ and receiving the first and secondvoltage signals through the signal receiving lines Y₀ and Y₁,respectively. The first and second charge/discharge signals are out ofphase, and may have the same charging level (FIG. 3B) or differentcharging levels (FIG. 10).

How a sensing method executing a single-stage charge/discharge operationaccording to the present invention works can be understood from thefollowing derivation. When Position 1 at lines Y₀ and X₁ is touched, andmeanwhile the window 20 moves to a scan position as shown in FIG. 9, thevoltage y0 sensed at the signal receiving line Y₀ varies with the phasex1 of the signal transmitting line X₁. Alternatively, if it is Position2 at lines Y₁ and X₁ touched, the voltage y1 sensed at the signalreceiving line Y₁ varies with the phase x1 of the signal transmittingline X₁; if it is Position 3 at lines Y₁ and X₀ touched, the voltage y1sensed at the signal receiving line Y₁ varies with the phase x0 of thesignal transmitting line X₀; and if Position 4 at lines Y₀ and X₀ istouched, the voltage y0 sensed at the signal receiving line Y₀ varieswith the phase x0 of the signal transmitting line X₀. Accordingly, ifPosition 4-1 in the middle of Position 4 and Position 1 is touched, thevoltage y0 sensed at the signal receiving line Y₀ varies with both thephase x0 of the signal transmitting line X₀ and the phase x1 of thesignal transmitting line X₁ with substantially equal effects; ifPosition 4-2 in the middle of Position 4 and Position 2 is touched, eachof the voltages y0 and y1 sensed at the signal receiving lines Y₀ and Y₁varies with both the phase x0 of the signal transmitting line X₀ and thephase x1 of the signal transmitting line X₁ with substantially equaleffects; if Position 4-3 in the middle of Position 4 and Position 3 istouched, each of the voltages y0 and y1 sensed at the signal receivinglines Y₀ and Y₁ varies with the phase x0 of the signal transmitting lineX₀. Table 1 summarizes the correspondence of the touch control positionsto the sensed voltages.

TABLE 1 Sensed voltage at signal Control point receiving line Position 4y0 → x0 y1 = 0 Position 4-1 y0 → x0 + x1 y1 = 0 Position 4-2 y0 → x0 +x1 y1 → x0 + x1 Position 4-3 y0 → x0 y1 → x0

Furthermore, another eight neighboring window positions surrounding thewindow position as illustrated in FIG. 9, when scanned, also exhibitvoltage change effects on the signal receiving lines, e.g. lines Y₀ andY₁, to different extents for different control points, e.g. Positions 4,4-1, 4-2 and 4-3. Likewise, a plurality of characteristic values aregenerated by subtracting the voltage y1 sensed at the signal receivingline Y₁ from the voltage y0 sensed at the signal receiving line Y₀, anda characteristic value array A[p, q] is obtained. Once thecharacteristic value array A[p, q] is recorded, position information ofone or more control points on the capacitive-type panel can be estimatedsubsequently, wherein each control point is a position to which a fingeror other conductive object approaches on the capacitive-type panel.Table 2 exemplifies a 3*3 characteristic value array A[p, q], in whichdata associated with the nine window positions are correspondinglyallocated, and each array element corresponding to one window positionconsists of four characteristic values of the four control points 4,4-1, 4-2 and 4-3, respectively.

TABLE 2 0 −x0 −x0 −(x0 + x1) −x1 −x1 0 −x0 −x0 −(x0 + x1) −x1 −x1 0 x0x0 x0 + x1 x1 x1 0 0 0 0 0 0 0 0 0 0 0 0 x0 x0 x0 x0 + x1 x1 x1

It is understood from the above table that characteristic values varywith different window positions and different touch control points.Therefore, different data patterns of the characteristic array A[p, q]can be obtained. For example, as shown in Table 2, the characteristicvalues (y0−y1) have seven kinds of expressions, i.e. x0, −x0, x1, −x1,x0+x1, −(x0+x1) and 0. If the voltage x0 and the voltage x1 arenumerically unequal, as exemplified in FIG. 10, the data patterns of thecharacteristic array A[p, q] may be differentiated with up to sevendifferent characteristic values. If the voltage x0 is set to be 3V andthe voltage x1 is set to be −3V, which are numerically equal asillustrated in FIG. 3B, the characteristic values (y0−y1) could besimplified to a positive, a negative and zero, similar to the datapatterns described in the previous embodiments. Therefore, an analysiscan then be performed according to the data pattern of thecharacteristic value array A[p, q].

Take the simplified case as an example, position information of one ormore control point on the capacitive-type panel can be estimated in Step104 of FIG. 1. The control point is a position which a finger approachesor contacts on the capacitive-type panel. For example, if there is nofinger approaching or contacting the capacitive-type panel, all of thedata recorded into the characteristic value array A[p, q] as obtained inthe scanning steps during a preset time period are 0. On the other hand,if a finger is approaching or contacting an intersection of a signaltransmitting line and a signal receiving line, e.g. X₀ and Y₀, of thecapacitive-type panel, the characteristic value corresponding to thespecified position and eight characteristic values corresponding toeight surrounding positions form a 3*3 data array, e.g. the array asshown in FIG. 4A. Therefore, by performing an operation on a 3*3 dataarray, the position which a finger approaches or contacts on thecapacitive-type panel can be specified. For example, when the result ofthe operation meets a first pattern, e.g. the pattern as shown in FIG.4A, it is determined that the estimated control point is (X₀, Y₀) and anoffset vector associated with the control point is (X₀, Y₀) is 0. Thatis, when the characteristic value array A[p, q] includes a data patternas shown in FIG. 4A, it is realized that there is a control point at(X₀, Y₀). If the characteristic value array A[p, q] includes more thanone data pattern like the one shown in FIG. 4A with zero offset, it isrealized that there exists another control point at a specificintersection of a signal transmitting line and a signal receiving line.

In addition, when a part of the characteristic value array A[p, q] has adata pattern as shown in any one of FIGS. 4B-4D, it is also estimatedthat there exists one control point. The control point is not at theintersection but nearby the intersection (X₀, Y₀) with a second offsetvector 42, a third offset vector 43, or a fourth offset vector 44. Forexample, the data pattern shown in FIG. 4B indicates that a controlpoint is below the intersection (X₀, Y₀) (for example, the position(4-3) shown in FIG. 3), the data pattern shown in FIG. 4C indicates thata control point is at right side of the intersection (X₀, Y₀) (forexample, the position (4-1) shown in FIG. 3), and the data pattern shownin FIG. 4D indicates that a control point is at lower right of theintersection (X₀, Y₀) (for example, the position (4-2) shown in FIG. 3).Therefore, at the same wiring density, the resolution can be increasedto two times at two dimensions, and thus the overall resolution can beincreased to four times.

Please refer to FIG. 11, which illustrates an exemplified circuit of thecomparator circuit 18 shown in FIG. 9. In this example, a first stimulussignal Stimulus0 and a second stimulus signal Stimulus1 are received viarespective input terminals where a first capacitor 1101 and a secondcapacitor 1102 are coupled to the comparator 1108 for voltage balance.The stimulus signals may be provided by a signal source outside thecomparator circuit 18 or even outside the control device. Either byadjusting the voltage values of the first stimulus signal and secondstimulus signal or the capacitance values of the first capacitor 1101and second capacitor 1102, the voltages at the two input terminals canbe made equal to have the output voltage of the comparator 1108 besubstantially zero. In this way, the characteristic value y0−y1 can befurther simplified as a voltage difference Δ between the first stimulussignal and the second stimulus signal, e.g. Stimulus1-Stimulus0, acapacitance difference or a combination of voltage difference andcapacitance difference.

Table 3 gives an example derived from Table 1, wherein thecorrespondence of the touch control positions to the sensed voltages areexpressed by voltage difference between the first and second stimulussignals.

TABLE 3 Voltage difference between Control point stimulus signalsPosition 4 Δ = x0 Position 4-1 Δ = x0 + x1 Position 4-2 Δ = 0 Position4-3 Δ = 0

The single-stage charge/discharge operation according to the presentinvention is particularly suitable for use in a capacitive type panelthat complies with the following conditions. Firstly, a capacitancevalue between a signal receiving line Y₀ and ground has to be largeenough to make the effect resulting from the finger's touch on a point,e.g. Position 10, away from the scan window 20 negligible. In addition,a capacitance value between another signal receiving line Y₁ and groundhas also to be large enough to make the effect resulting from thefinger's touch on a point, e.g. Position 11, away from the scan window20 negligible. This condition may be inherently satisfied in specificpanels, or made satisfied by fine-tuning circuitry features of panels.Even if the condition is originally unsatisfied due to small linewidthor poor conductivity of the signal receiving line Y₀ or Y₁, thesituation can still be remedied by combining plural signal receivinglines as a group to conduct the sensing operation instead of the singlesignal receiving line. For example, the signal receiving lines Y_(—1)and Y₀ are electrically connected in parallel to function for thesensing operation instead of the single receiving line Y₀, and thesignal receiving lines Y₁ and Y₂ are electrically connected in parallelto function for the sensing operation instead of the single receivingline Y₁. In this way, the capacitance value of the signal receivinglines can be enlarged. Another condition is that a signal intensitysensed at a control point of the scan window 20, e.g. Position 4, has tobe much higher than a signal intensity sensed at a distant position,e.g. Position 10, thereby making the effect resulting from the finger'stouch on Position 10 negligible. Likewise, plural signal transmittinglines may be combined as a group, if necessary, to conduct the sensingoperation instead of the single signal receiving line. For example, thesignal transmitting lines X⁻¹ and X₀ are electrically connected inparallel to function for the sensing operation instead of the singletransmitting line X₀, and the signal transmitting lines X₁ and X₂ areelectrically connected in parallel to function for the sensing operationinstead of the single transmitting line X₁. In this way, the drivingcapability can be improved.

The capacitive-type panel developed based on the principle of thepresent invention is advantageous as it can still work when thecapacitance value at the neighboring region defined by the two sets ofsignal transmitting lines and the two sets of signal receiving lines isvery small or approaches zero.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

What is claimed is:
 1. A method for sensing a control point on acapacitive-type panel, where a conductive object approaches or contacts,the capacitive-type panel including M signal transmitting lines and Nsignal receiving lines defining M*N neighboring regions, the methodbeing executed by a sensing device and comprising steps of: receiving afirst voltage signal and a second voltage signal through two sets ofsignal receiving lines selected from the N signal receiving lines inresponse to a first charge/discharge signal and a secondcharge/discharge signal transmitted through two sets of signaltransmitting lines selected from the M signal transmitting lines,respectively, during a specified time period, wherein the firstcharge/discharge signal and the second charge/discharge signal are outof phase; and operating the first voltage signal and the second voltagesignal to generate a characteristic value for a neighboring regiondefined by the two sets of signal transmitting lines and the two sets ofsignal receiving lines, wherein the above steps are repetitivelyperformed so as to generate a plurality of characteristic values for aplurality of neighboring regions defined by different combinations ofsignal transmitting lines and signal receiving lines, and positioninformation of at least one control point on the capacitive-type panelis estimated according to the characteristic values.
 2. The method forsensing a control point according to claim 1, wherein the firstcharge/discharge signal is a charge signal rising from a low voltage toa high voltage, and the second charge/discharge signal is a dischargesignal falling from a high voltage to a low voltage; and the step ofoperating the first voltage signal and the second voltage signal togenerate the characteristic value for the neighboring region defined bythe two sets of signal transmitting lines and the two sets of signalreceiving lines comprises: generating a voltage difference value or afunction value equivalent to the voltage difference of the first voltagesignal and the second voltage signal; and using the voltage differencevalue or function value equivalent to the voltage difference as thecharacteristic value.
 3. The method for sensing a control pointaccording to claim 1, wherein the characteristic values are configuredas a characteristic value array, and the position information of the atleast one control point on the capacitive-type panel is estimatedaccording to a data pattern included in the characteristic value array.4. The method for sensing a control point according to claim 3, whereinthe position information of the al least one control point is estimatedby: performing an operation on a 3*3 data array selected from thecharacteristic value array; determining the position information of thecontrol point and a first offset vector when the result of the operationmeets a first condition; determining the position information of thecontrol point and a second offset vector when the result of theoperation meets a second condition; determining the position informationof the control point and a third offset vector when the result of theoperation meets a third condition; and determining the positioninformation of the control point and a fourth offset vector when theresult of the operation meets a fourth condition.
 5. A device forsensing a control point on a capacitive-type panel, where a conductiveobject approaches or contacts, the capacitive-type panel including Msignal transmitting lines and N signal receiving lines defining M*Nneighboring regions, the device comprising: a charge/discharge signalgenerator electrically connected to the M signal transmitting lines, thecharge/discharge signal generator inputting a first charge/dischargesignal and a second charge/discharge signal respectively to two sets ofsignal transmitting lines selected from the M signal transmitting linesduring a specified time period, wherein the first charge/dischargesignal and the second charge/discharge signal are out of phase; and avoltage signal processor electrically connected to the N signalreceiving lines, the voltage signal processor receiving a first voltagesignal and a second voltage signal respectively from two sets of signalreceiving lines selected from the N signal receiving lines during thespecified time period, operating the first voltage signal and the secondvoltage signal to generate a characteristic value for a neighboringregion defined by the two sets of signal transmitting lines and the twosets of signal receiving lines, wherein the above steps are repetitivelyperformed so as to generate a plurality of characteristic values for aplurality of neighboring regions defined by different combinations ofsignal transmitting lines and signal receiving lines, and positioninformation of at least one control point on the capacitive-type panelis estimated according to the characteristic values.
 6. The device forsensing a control point according to claim 5, wherein the firstcharge/discharge signal is a charge signal rising from a low voltage toa high voltage, and the second charge/discharge signal is a dischargesignal falling from a high voltage to a low voltage; and the step ofoperating the first voltage signal and the second voltage signal togenerate the characteristic value for the neighboring region defined bythe two sets of signal transmitting lines and the two sets of signalreceiving lines comprises: generating a voltage difference value or afunction value equivalent to the voltage difference of the first voltagesignal and the second voltage signal; and using the voltage differencevalue or function value equivalent to the voltage difference as thecharacteristic value.
 7. The device for sensing a control pointaccording to claim 5, wherein the characteristic values are configuredas a characteristic value array, and the position information of the atleast one control point on the capacitive-type panel is estimatedaccording to a data pattern included in the characteristic value array.8. The device for sensing a control point according to claim 7, whereinthe position information of the al least one control point is estimatedby: performing an operation on a 3*3 data array selected from thecharacteristic value array; determining the position information of thecontrol point and a first offset vector when the result of the operationmeets a first condition; determining the position information of thecontrol point and a second offset vector when the result of theoperation meets a second condition; determining the position informationof the control point and a third offset vector when the result of theoperation meets a third condition; and determining the positioninformation of the control point and a fourth offset vector when theresult of the operation meets a fourth condition.